Various sensors for pulse oximeters have been designed since oximetry came into common use in the early 1980s. Presently, about two-thirds of sensors used in the United States are of the disposable or single-use type. For example, the Goodman et al U.S. Pat. No. 4,830,014, assigned to Nellcor Incorporated, teaches emitter and detector elements of the sensor combined on al flexible strip, coated with adhesive, and then wrapped around a body part such as the finger or, in the case of babies, a foot. Since a disposable sensor at a minimum requires red and infrared light-emitting-diodes (LED), a photodetector and a shielded cable, disposable devices are a severe ongoing expense for the user.
Nellcor has developed a recycling program in which the sensor can be reused two or three times after being reconditioned at the factory; but, nevertheless, the cost for each patient use is not less than $7.00 and can be up to double that amount. Several attempts have been made by various companies to make some parts of the sensor more reusable so as to avoid the cost of replacing the entire device. For example, Swedlow et al of Nellcor have designed a sensor in which only the light emitters are discarded, the cable and detector portion being retained (U.S. Pat. No. 5,209,230).
Amundsen et al describe a reusable cable which is inserted into a tubular disposable finger cover made of paper or plastic which is designed to fit over a digit (U.S. Pat. No. 5,437,275).
Another attempt to avoid the cost of disposable sensors is that of Thomas et al (U.S. Pat. No. 5,170,786) whose group designed a probe using a disposable wrap with two square holes and a complimentary cable with sensing elements which plug into the holes in the fastening wrap. A flange surrounds the sensors and is an important element in stabilizing the detectors and emitters in this design. The sensors of this design project above the surface of the wrap. In practice, the wrap of this design relies on an adhesive coating for attachment to the skin and for stabilization of the sensing elements onto the wrap.
Pediatric sensors present the additional problem of the fragility of neonatal skin, especially if the infant is premature. Skin breakdown is a constant concern when sticky adhesive sensors are used in this very young patient population.
The present design advances the state-of-the-art since the cable and sensing elements are reusable and even the foot wrap which holds the sensing elements can be reused many times, making it very economical for the user. The present design does not require an adhesive for attachment to the skin or for stabilizing the sensors to the wrap. The wrap, itself, is made of very thin, semi-transparent rubberlike material, such as Kraton. The wrap is perforated to allow egress of perspiration and the perforations also assist in stabilization of the wrap around the foot.
The slight elasticity of the rubbery material helps it to conform to the infant's foot and gives just enough snugness to stabilize the sensor. The adjustable feature to be described permits easy adaptation to a range of pediatric foot sizes. Finally, the shape of the receptacles and their elasticity facilitates both insertion and removal of the sensing elements and stabilizes the emitters and photodetector during use.
A primary object of the invention is to provide an adjustable pulse oximetry sensor for pediatric use which is reusable and therefore cost effective.
A further object of the invention is to provide a pediatric pulse oximetry sensor which attaches to the patient's foot without requiring the use of adhesives.
A further object of the invention is to provide a reusable pulse oximetry sensor for pediatric use wherein the connecting cable, the sensing elements, and the foot wrap are all usable many times.
Another object of the invention is to provide a foot wrap for use in pediatric oximetry sensors which not only avoids the use of adhesive, but is also perforated to allow flow of perspiration.
Yet another object of the invention is to use resilient receptacles carried by the foot wrap and which are sized relative to the sensors so that the receptacles stretch to receive a sensor and resiliently grip and enclose the sensor to hold it securely in position.
Further, objects and advantages of the invention will become apparent from the following description and the drawings, wherein: